阅读说明：本技术 逆变器装置 (Inverter device ) 是由 牧村雄基 松田将宜 藤崎翔吾 斋藤真敏 于 2020-04-14 设计创作，主要内容包括：提供一种逆变器装置,能够在脉动电压的容许范围内使电解电容器的内部温度更快地上升,缩短未动作时间。包括电解电容器(1)、逆变器电路(2)、温度传感器(4)以及控制装置(3)。控制装置(3)在由温度传感器(4)检测到的电解电容器(1)的周边温度低于规定温度的情况下,在马达(5)的通常运转开始前,对逆变器电路(2)的特定开关元件进行导通驱动,从而在使马达(5)停止不变的状态下,执行预热运转,所述预热运转以规定的上升率使能将直流电压的脉动电压控制在容许范围内的电流流过马达(5)。(Provided is an inverter device capable of increasing the internal temperature of an electrolytic capacitor more quickly within an allowable range of a ripple voltage and shortening a non-operation time. The device comprises an electrolytic capacitor (1), an inverter circuit (2), a temperature sensor (4), and a control device (3). When the ambient temperature of the electrolytic capacitor (1) detected by the temperature sensor (4) is lower than a predetermined temperature, the control device (3) drives a specific switching element of the inverter circuit (2) to be turned on before the normal operation of the motor (5) is started, and executes a warm-up operation in which a current for controlling the ripple voltage of the DC voltage within an allowable range is allowed to flow to the motor (5) at a predetermined rate of increase while the motor (5) is kept stopped.)

1. An inverter device, characterized by comprising:

an electrolytic capacitor for smoothing an input voltage to generate a direct current voltage;

an inverter circuit that generates an alternating-current voltage from the direct-current voltage to drive a motor;

a temperature sensor for detecting a temperature of the electrolytic capacitor or a temperature around the electrolytic capacitor; and

a control device that controls driving of a plurality of switching elements included in the inverter circuit,

the control device performs a warm-up operation in which a current for controlling a ripple voltage of the dc voltage within an allowable range is allowed to flow to the motor at a predetermined rate of increase by turning on a specific switching element selected from the plurality of switching elements before a normal operation of the motor is started when a temperature detected by the temperature sensor is lower than a predetermined temperature, and in a state where the motor is not stopped.

2. The inverter device according to claim 1,

the control device changes a rate of increase of the current flowing through the motor based on the input voltage and the temperature detected by the temperature sensor.

3. The inverter device according to claim 2,

the control device changes the rate of increase of the current flowing through the motor in a decreasing direction as the input voltage increases.

4. The inverter device according to claim 3,

the control device changes the value of the current flowing through the motor in the direction of decreasing as the input voltage increases.

5. The inverter device according to any one of claims 2 to 4,

the control device changes the rate of increase of the current flowing through the motor in a direction of decrease as the temperature detected by the temperature sensor decreases.

6. The inverter device according to claim 5,

the control device may change the value of the current flowing through the motor in a direction to decrease as the temperature detected by the temperature sensor decreases.

7. The inverter device according to any one of claims 1 to 6,

the control device changes a rate of increase of the current flowing through the motor in a multi-stage manner with time during the warm-up operation.

8. The inverter apparatus according to claim 7,

the control device changes the rate of increase of the current flowing through the motor in a direction to increase as time elapses from the start of the warm-up operation.

9. The inverter device according to any one of claims 1 to 8,

the control device limits a value of a current flowing through the motor in the normal operation after the warm-up operation is completed.

Technical Field

The present invention relates to an inverter device that generates an ac voltage from a dc voltage smoothed by an electrolytic capacitor and drives a motor.

Background

The conventional inverter device is provided with an electrolytic capacitor for smoothing a power supply voltage of the inverter circuit, and selectively drives 3 switching elements on the upper phase side and 3 switching elements on the lower phase side of the inverter circuit to generate U, V, W three-phase voltages from the dc voltage to drive the motor.

In addition, in such an inverter device, particularly in-vehicle inverter devices, there are cases where the inverter device is used in a low-temperature environment, and when an electrolytic capacitor is used in such an environment, the internal resistance component (equivalent series resistance) of the electrolytic capacitor increases, the ripple voltage increases, and there is a risk that the voltage applied to the electrolytic capacitor exceeds the withstand voltage thereof or becomes a counter voltage, and the electrolytic capacitor is broken.

As a method for solving this problem, it is conceivable to reduce the ripple voltage by increasing the electrolytic capacitor and reducing the internal resistance component, but there is a problem that the cost rises and the size increases. Therefore, as a method for reducing the internal resistance component, a method has been developed in which a preheating mode for raising the internal temperature of the electrolytic capacitor is executed while the motor is stopped (see, for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012-222925

Disclosure of Invention

Technical problem to be solved by the invention

Here, when the internal resistance component of the electrolytic capacitor is reduced to reduce the ripple voltage, it is desirable to increase the internal temperature of the electrolytic capacitor for a long time with a small current. However, such a conventional method has a problem that the time of the warm-up mode, that is, the non-operation time from the start instruction of the motor to the start of the rotation of the motor becomes long.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an inverter device capable of increasing the internal temperature of an electrolytic capacitor more quickly within an allowable range of a ripple voltage to shorten a non-operation time.

Means for solving the problems

The inverter device of the present invention is characterized by comprising: an electrolytic capacitor for smoothing an input voltage to generate a direct current voltage; an inverter circuit for generating an alternating voltage from the direct voltage to drive the motor; a temperature sensor for detecting the temperature of the electrolytic capacitor or the ambient temperature thereof; and a control device that controls driving of the plurality of switching elements included in the inverter circuit, wherein, when the temperature detected by the temperature sensor is lower than a predetermined temperature, a specific switching element selected from the plurality of switching elements is driven to be turned on before a normal operation of the motor is started, and thereby, a warm-up operation is performed in a state where the motor is stopped, the warm-up operation allowing a current for controlling a ripple voltage of the dc voltage within an allowable range to flow through the motor at a predetermined rate of increase.

In the inverter device according to the second aspect of the present invention, in the above-described invention, the control device changes the rate of increase of the current flowing through the motor based on the input voltage and the temperature detected by the temperature sensor.

In the inverter device according to the third aspect of the present invention, in the above-described invention, the control device changes the rate of increase of the current flowing through the motor in the direction of decrease as the input voltage increases.

In the inverter device according to the fourth aspect of the present invention, in the above-described invention, the controller changes the value of the current flowing through the motor in the direction of decreasing as the input voltage increases.

In the inverter device according to a fifth aspect of the present invention, in the second to fourth aspects of the present invention, the control device changes the rate of increase of the current flowing through the motor in the direction of decrease as the temperature detected by the temperature sensor decreases.

In the inverter device according to a sixth aspect of the present invention, in the above-described invention, the control device changes the value of the current flowing through the motor in the decreasing direction as the temperature detected by the temperature sensor decreases.

In the inverter device according to the seventh aspect of the present invention, in each of the above aspects of the present invention, the control device changes the rate of increase of the current flowing through the motor in multiple stages with time during the warm-up operation.

In the inverter device according to the eighth aspect of the present invention, in the above-described invention, the control device changes the rate of increase of the current flowing through the motor in a direction to increase as time elapses from the start of the warm-up operation.

In the inverter device according to the ninth aspect of the present invention, in each of the above aspects of the present invention, the control device limits the value of the current flowing through the motor in the normal operation after the completion of the warm-up operation.

Effects of the invention

The inverter device of the invention comprises: an electrolytic capacitor for smoothing an input voltage to generate a direct current voltage; an inverter circuit for generating an alternating voltage from the direct voltage to drive the motor; a temperature sensor for detecting the temperature of the electrolytic capacitor or the ambient temperature thereof; and a control device that controls driving of the plurality of switching elements included in the inverter circuit, wherein, when the temperature detected by the temperature sensor is lower than a predetermined temperature, a specific switching element selected from the plurality of switching elements is driven to be turned on before a normal operation of the motor is started, and thereby, a warm-up operation is performed in a state where the motor is stopped, the warm-up operation causing a current capable of controlling a ripple voltage of the dc voltage within an allowable range to flow through the motor at a predetermined rate of increase, and therefore, the ripple voltage of the dc voltage can be suppressed within the allowable range, and the internal temperature of the electrolytic capacitor can be increased more quickly.

This makes it possible to avoid destruction of the electrolytic capacitor in a low-temperature environment, and to shorten the time required for the warm-up operation (non-operation time) from the start instruction to the start of rotation of the motor.

In this case, since the peak value of the ripple voltage becomes larger as the input voltage becomes higher and the temperature of the electrolytic capacitor becomes lower, the control device according to the second aspect of the present invention changes the rate of increase of the current flowing through the motor based on the input voltage and the temperature detected by the temperature sensor, thereby enabling the internal temperature of the electrolytic capacitor to be increased more safely and efficiently by the warm-up operation.

For example, the control device according to the third aspect of the present invention changes the rate of increase of the current flowing through the motor in the direction of decrease as the input voltage increases, and thereby the internal temperature of the electrolytic capacitor can be safely and quickly increased by the warm-up operation.

In this case, the higher the input voltage is, the more the control device as in the fourth aspect of the present invention changes the value of the current flowing through the motor in the direction of decreasing at the start of the warm-up operation, and the breakdown of the electrolytic capacitor due to the ripple voltage of the dc voltage can be avoided more effectively.

In addition, for example, the control device according to the fifth aspect of the present invention changes the rate of increase of the current flowing through the motor in the direction of decrease as the temperature detected by the temperature sensor decreases, and can safely and quickly increase the internal temperature of the electrolytic capacitor even in the warm-up operation.

In this case, the control device as in the sixth aspect of the present invention can more effectively avoid the breakdown of the electrolytic capacitor due to the ripple voltage of the dc voltage by changing the value of the current flowing through the motor in the decreasing direction as the temperature detected by the temperature sensor decreases.

Here, the internal resistance component of the electrolytic capacitor tends to be extremely large at low temperature and to be drastically reduced with an increase in internal temperature. Therefore, the control device according to the seventh aspect of the present invention changes the rate of increase of the current flowing through the motor in multiple stages with the elapse of time during the warm-up operation, and for example, as in the eighth aspect of the present invention, the control device changes the rate of increase of the current flowing through the motor in the direction of increasing as the time elapses from the start of the warm-up operation, thereby making it possible to increase the internal temperature of the electrolytic capacitor more safely and quickly.

In addition, if the control device as in the ninth aspect of the present invention restricts the value of the current flowing through the motor during the normal operation after the completion of the warm-up operation, it is possible to more effectively avoid the electrolytic capacitor from being damaged in the low-temperature environment.

Drawings

Fig. 1 is a schematic circuit diagram of an inverter device to which an embodiment of the present invention is applied.

Fig. 2 is a flowchart illustrating a warm-up operation of the control device of the inverter device of fig. 1.

Fig. 3 is a diagram illustrating an energization state of the inverter circuit in the warm-up operation of fig. 2.

Fig. 4 is a diagram illustrating the warm-up condition used in the flowchart of fig. 2.

Fig. 5 is a diagram for explaining an example of the warm-up operation executed in the flowchart of fig. 2.

Fig. 6 is a diagram illustrating another example of the warm-up operation executed in the flowchart of fig. 2.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a circuit diagram showing a schematic configuration of an inverter device IV to which an embodiment of the present invention is applied. The inverter device IV of the embodiment is a vehicle-mounted inverter device that is provided integrally with a compressor, not shown, constituting a vehicle air conditioner and mounted on a vehicle. An inverter device IV according to the embodiment is configured to smooth an input voltage HV from a battery (dc power supply) BAT mounted on a vehicle by an electrolytic capacitor 1, generate an ac voltage from the smoothed dc voltage, and drive a motor 5 as an electric motor, and includes the electrolytic capacitor 1, an inverter circuit 2, a control device 3, and a temperature sensor 4.

The electrolytic capacitor 1 is composed of a large-capacity aluminum electrolytic capacitor for smoothing an input voltage HV to a dc voltage. Although such an aluminum electrolytic capacitor is small and inexpensive, its internal resistance component (equivalent series resistance) ESR is generally large because of the resistance of the electrolytic solution, the resistance of the electrolytic paper, and the like. For example, as in the case of use in a low-temperature environment, the present invention has the following features: the internal resistance component ESR becomes larger as the internal temperature of the electrolytic capacitor 1 is lower, and particularly, the internal resistance component ESR becomes larger rapidly as the internal temperature becomes lower.

The inverter circuit 2 is provided to supply the dc voltage smoothed by the electrolytic capacitor 1 as a power supply voltage. The inverter circuit 2 generates three-phase voltages Vu, Vv, Vw from the dc voltage, and supplies the three-phase voltages to a motor (three-phase brushless motor) 5 as a motor, and is configured to include, for example, 3 switching elements (IGBTs) 6u, 6v, 6w on the upper phase side and 3 switching elements (IGBTs) 7u, 7v, 7w on the lower phase side.

A control device 3 is connected to the inverter circuit 2. The control device 3 is configured by a microcomputer provided with a processor, and is a device for controlling on/off drive of the 6 switching elements 6u to 6w, 7u to 7w of the inverter circuit 2 to appropriately operate the motor 5, and is configured to cause a current (phase current) for limiting a pulsating voltage of a direct current voltage applied to the electrolytic capacitor 1 within an allowable range to flow through the motor 5 by controlling a duty ratio of a pulse width modulation (hereinafter referred to as "PWM") signal for on/off drive of the respective switching elements 6u to 6w, 7u to 7w of the inverter circuit 2 before start of normal operation of the motor 5 when a temperature of the electrolytic capacitor 1 is lower than a predetermined temperature T1, and to stop the motor 5, and in such a state, temperature rise of the electrolytic capacitor 1 can be performed by directly utilizing joule heat generated in an internal resistance component (equivalent series resistance) ESR of the electrolytic capacitor 1 The preheating operation of (1).

In this case, the control device 3 causes the current to flow to the motor 5 at a predetermined rate of increase during the warm-up operation, and in the embodiment, the rate of increase is changed in accordance with the input voltage HV from the battery BAT and the temperature around the electrolytic capacitor 1. In the embodiment, the temperature sensor 4 is disposed in the vicinity of the electrolytic capacitor 1. The temperature sensor 4 detects the ambient temperature Tc of the electrolytic capacitor 1 (the temperature around the electrolytic capacitor 1) and outputs the detected temperature to the control device 3, and the temperature sensor 4 is constituted by, for example, a thermocouple, a positive thermistor, or the like.

In the embodiment, the electrolytic capacitor 1 is mounted on the same substrate as the inverter circuit 2 and housed in the same space as the inverter circuit 2, and the temperature sensor 4 is also disposed on the substrate near the electrolytic capacitor 1, but the present invention is not limited thereto, and the temperature of the electrolytic capacitor 1 itself may be detected by the temperature sensor 4. In the embodiment, the ambient temperature Tc of the electrolytic capacitor 1 is treated as the temperature of the electrolytic capacitor 1.

The warm-up conditions shown in fig. 4 are preset in the control device 3. The warm-up operating conditions of the embodiment are a data table set based on the ambient temperature Tc of electrolytic capacitor 1 detected by temperature sensor 4 and the input voltage HV from battery BAT. In this case, under the warm-up condition of fig. 4, only the portions indicated by 10/10 and 5/10 mean that the warm-up is not performed. 10/10 indicates a normal starting current value, and 5/10 indicates a half value thereof.

In the figure, t1 to t7 represent the energization time of the motor 5, and the portions indicated by the fraction connected by the arrow basically represent the current values at the start and the end of the warm-up operation of the motor 5, meaning that these indicated portions perform the warm-up operation. The fraction is also the magnitude of the current value relative to the usual starting current (10/10), e.g. 2/10 means one fifth of the usual starting current (10/10).

In fig. 4, the energization time t1 to t5 is set to t1 < t2 < t3 < t4 < t 5. In addition, in the embodiment, the energization times t6 and t7 are set to the relationship of t7 < t 6. Further, the longer the energization time, the smaller the difference between the current value at the start of the warm-up operation and the current value at the completion thereof, the lower the rate of increase of the current, and the shorter the energization time, the larger the difference between the current value at the start of the warm-up operation and the current value at the completion thereof, and the higher the rate of increase of the current.

The energization time t1 to t7, the current value at the start of the warm-up operation, and the current value at the completion of the warm-up operation (1/10, 2/10, 3/10, 5/10, 6/10, 7/10), that is, the rate of increase in current determined by these values are determined experimentally in advance for the energization time, the current value, and the rate of increase in current, which are capable of suppressing the pulsating voltage of the direct current in the electrolytic capacitor 1 within the allowable range under the combined conditions of the ambient temperature Tc and the input voltage HV. When the warm-up operation is performed, the control device 3 selects any one of the ambient temperature Tc and the input voltage HV when the start instruction of the motor 5 is input, and performs the warm-up operation of the electrolytic capacitor 1.

Next, the warm-up operation performed by the control device 3 will be specifically described with reference to the flowchart of fig. 2. When the start instruction of the motor 5 is given, the control device 3 first determines whether or not the ambient temperature Tc of the electrolytic capacitor 1 detected by the temperature sensor 4 is lower than the predetermined temperature T1 in step S1 of the flowchart of fig. 2. In the embodiment, the predetermined temperature T1 is different depending on the input voltage HV. That is, the higher the input voltage HV, the lower the temperature of the electrolytic capacitor 1 (the ambient temperature Tc is used in the embodiment), and the larger the peak value of the ripple voltage of the dc voltage applied to the electrolytic capacitor 1 becomes.

Therefore, in this embodiment, the predetermined temperature T1 is-24 ℃ when the input voltage HV is lower than 200V, the predetermined temperature T1 is-19 ℃ when the input voltage HV is 200V or more and lower than 250V, and the predetermined temperature T1 is-14 ℃ when the input voltage HV is 250V or more and lower than 300V. Similarly, the predetermined temperature T1 is-9 ℃ when the input voltage HV is 300V or more and less than 350V, and the predetermined temperature T1 is-4 ℃ when the input voltage HV is 350V or more and less than 400V. When the input voltage HV is 400V or more and less than 450V, the predetermined temperature T1 is set to +1 ℃, and when the input voltage HV is 450V or more and less than 500V, the predetermined temperature T1 is set to +6 ℃.

When the ambient temperature Tc of the electrolytic capacitor 1 detected by the temperature sensor 4 is equal to or higher than the predetermined temperature T1 in step S1, the controller 3 proceeds to step S7 to start the motor 5 with the normal starting current (10/10) to start the normal operation. That is, the preheating operation of the electrolytic capacitor 1 is not performed until the normal operation of the motor 5 is started.

On the other hand, when the ambient temperature Tc is lower than the predetermined temperature T1 in step S1, the control device proceeds to step S2 to determine whether the elapsed time tpass after the completion of the previous warm-up operation is shorter than the predetermined time tpass 1. When the predetermined time tpass1 or more has elapsed after the completion of the previous warm-up operation, the control device 3 proceeds to step S6.

When the elapsed time tpass after the completion of the previous warm-up operation is shorter than the predetermined time tpass1, the controller 3 proceeds to step S3 to check the input voltage HV from the battery BAT. Next, the process proceeds to step S4, the warm-up conditions in fig. 4 are checked based on the ambient temperature Tc and the input voltage HV, any one of the warm-up conditions is selected and determined, and the warm-up operation of the electrolytic capacitor 1 is started.

During the warm-up operation, the control device 3 calculates the duty ratio of the PWM signal based on the determined warm-up condition. Then, for example, the switching device 6u on the upper phase side of the inverter circuit 2 is driven to be turned on by the PWM signal of the calculated duty ratio, and for example, the switching devices 7v and 7w on the lower phase side are driven to be turned on. Accordingly, as shown by a thick solid line in fig. 3, the inverter circuit 2 and the motor 5 perform the warm-up operation with a current flow determined as a warm-up operation condition in which the ripple voltage of the dc voltage is within the allowable range.

In this case, the switching elements of the inverter circuit 2 that are driven to be turned on are fixed to the switching element 6u, for example, on the upper phase side and the switching elements 7v, 7w, for example, on the lower phase side, and therefore the motor 5 remains stopped. In this way, while the current is being supplied to the motor 5, the electrolytic capacitor 1 is heated by joule heat generated in its internal resistance component ESR, and thus the temperature is raised.

(1) Preheating operation (one of them)

Next, an example of the actual warm-up operation based on the respective warm-up operation conditions in fig. 4 will be described. As described above, since the peak value of the ripple voltage of the dc voltage applied to the electrolytic capacitor 1 becomes larger as the input voltage HV is higher and the temperature of the electrolytic capacitor 1 (the ambient temperature Tc is used in the embodiment) is lower, the control device 3 sets the current value flowing through the motor 5 to 5/10 (fixed value) when the input voltage HV is 200V or more and less than 300V in a situation where the ambient temperature Tc of the electrolytic capacitor 1 is-24 ℃ or more and-20 ℃ or less. This is half the current value of the normal start-up current (10/10).

In the case where the ambient temperature Tc is-19 ℃ or higher and-15 ℃ or lower, the value of the current flowing through the motor 5 is similarly 5/10 even when the input voltage HV is 250V or higher and lower than 350V. In the case where the ambient temperature Tc is-14 ℃ or higher and-10 ℃ or lower, the value of the current flowing through the motor 5 is also 5/10 even when the input voltage HV is 300V or higher and lower than 400V. In the case where the ambient temperature Tc is-9 ℃ or higher and-5 ℃ or lower, the value of the current flowing through the motor 5 is also 5/10 even when the input voltage HV is 350V or higher and lower than 450V. In the case where the ambient temperature Tc is equal to or higher than-4 ℃ and equal to or lower than 0 ℃, the value of the current flowing through the motor 5 is similarly 5/10 even when the input voltage HV is equal to or higher than 400V and lower than 500V. In the case where the ambient temperature Tc is +1 ℃ or higher and +5 ℃ or lower, the value of the current flowing through the motor 5 is also 5/10 even when the input voltage HV is 450V or higher and lower than 500V.

Accordingly, in a situation where the ambient temperature Tc is relatively high, the input voltage HV is lower, the input voltage Tc is lower, or the input voltage HV is higher, and at a high ambient temperature Tc, a fixed current (5/10) having a half value of the normal starting current (10/10) flows through the motor 5, so that the ripple voltage of the dc voltage applied to the electrolytic capacitor 1 is controlled within the allowable range, and the electrolytic capacitor 1 is warmed up.

(2) Preheating operation (the second)

Next, as shown in fig. 4, when the input voltage HV is lower than 300V in a situation where the ambient temperature Tc is-25 ℃ or lower, when the input voltage HV is 300V or higher and lower than 350V in a situation where the ambient temperature Tc is-24 ℃ or higher and-20 ℃ or lower, when the input voltage HV is 350V or higher and lower than 400V in a situation where the ambient temperature Tc is-19 ℃ or higher and-15 ℃ or lower, when the input voltage HV is 400V or higher and lower than 450V in a situation where the ambient temperature Tc is-14 ℃ or higher and-10 ℃ or lower, and when the input voltage HV is 450V or higher and lower than 500V in a situation where the ambient temperature Tc is-9 ℃ or higher and-5 ℃ or lower, the control device 3 performs a warm-up operation in which the current flowing through the motor 5 is increased at a predetermined rate of increase.

For example, when the input voltage HV is lower than 200V in a situation where the ambient temperature Tc is-29 ℃ or higher and-25 ℃ or lower, the current value at the start of the warm-up operation is 3/10 (three tenths of the normal starting current), the current value at the completion is 7/10 (seven tenths of the normal starting current), and the energization time is t 1. Thereby, as shown in fig. 5, the current flows through the motor 5 at a rate of rise from 3/10 to 7/10 during time t 1. In this case, although the ripple voltage of the dc voltage in the electrolytic capacitor 1 increases from the start of the warm-up operation, the internal resistance component ESR decreases as the internal temperature of the electrolytic capacitor 1 increases, and therefore, the ripple voltage reaches MAX (maximum value) at a certain time, and then gradually decreases even when the current increases. Further, by increasing the current flowing through the motor 5 at the rate of increase shown in fig. 5, the internal temperature of the electrolytic capacitor 1 can be increased earlier than in the case where a fixed current is flowing.

On the other hand, similarly, even when the input voltage HV is lower than 200V, the current value at the start of the warm-up operation is 2/10 (two tenths of the normal starting current), the current value at the completion is 6/10 (six tenths of the normal starting current), and the energization time is t2 in the case where the ambient temperature Tc is-39 ℃ or higher and-35 ℃ or lower. In this case, the difference between current value 2/10 at the start of the warm-up operation and current value 6/10 at the completion thereof is equal to the difference between current values at-29 ℃ or higher and-25 ℃ or lower at the ambient temperature Tc (difference between 3/10 and 7/10), but since the energization time t2 is longer than t1 as described above, the current increase rate from the start to the completion of the warm-up operation is lower than the current increase rate at the time of-29 ℃ or higher and-25 ℃ or lower at the ambient temperature Tc. That is, even with the same input voltage HV, the control device 3 changes the rate of increase of the current in the warm-up operation in the direction of decrease as the ambient temperature Tc becomes lower.

In addition, the value of the current flowing through the motor 5 at the start of the warm-up operation was reduced to 2/10 even at an ambient temperature of-39 ℃ or higher and-35 ℃ or lower, as compared with 3/10 at an ambient temperature of-29 ℃ or higher and-25 ℃ or lower, respectively. That is, even with the same input voltage HV, the lower the ambient temperature Tc, the more the control device 3 changes the current value disclosed for the warm-up operation in the direction of decreasing.

Similarly, even in a situation where the ambient temperature Tc is equal to or higher than-29 ℃ and equal to or lower than-25 ℃, for example, when the input voltage HV is equal to or higher than 450V and lower than 500V, the current value at the start of the warm-up operation is 1/10 (one tenth of the normal starting current), the current value at the completion is 5/10 (five tenths of the normal starting current), and the energization time is t 5. In this case, the difference between current value 1/10 at the start of the warm-up operation and current value 5/10 at the completion thereof is the same as the difference (difference between 3/10 and 7/10) when input voltage HV is lower than 200V, but since energization time t5 is longer than t1 as described above, the rate of increase in current from the start of the warm-up operation to the completion thereof is lower than that when input voltage HV is lower than 200V. That is, even with the same ambient temperature Tc, the higher the input voltage HV, the more the control device 3 changes the rate of increase of the current in the warm-up operation in the direction of decrease.

In addition, the value of the current flowing through the motor 5 at the start of the warm-up operation is reduced to 1/10 even when the input voltage HV is 450V or more and less than 500V, as compared with 3/10 when the input voltage HV is less than 200V. That is, even with the same ambient temperature Tc, the higher the input voltage HV, the more the control device 3 changes the current value disclosed for the warm-up operation in the direction of decreasing.

The other ambient temperatures Tc in fig. 4 and the warm-up conditions in the input voltage HV also have the same tendency, and even at the same input voltage HV, the lower the ambient temperature Tc, the more the control device 3 changes the current value disclosed in the warm-up operation in the direction of decreasing, and even at the same ambient temperature Tc, the higher the input voltage HV, the more the control device 3 changes the current value disclosed in the warm-up operation in the direction of decreasing.

When the warm-up operation is completed in step S5 of fig. 2, the control device 3 proceeds to step S6, and starts the normal operation by driving the motor 5 with a starting current 5/10 that is half the above-described normal starting current (10/10). That is, after the warm-up operation is completed, the controller 3 limits the value of the current flowing through the motor 5 by the normal value (10/10) (5/10).

As described above, when the ambient temperature Tc detected by the temperature sensor 4 is lower than the predetermined temperature T1, the control device 3 performs the warm-up operation in which the current capable of controlling the ripple voltage of the dc voltage within the allowable range is caused to flow through the motor 5 at the predetermined rate of increase by driving the specific switching elements 6u, 7v, and 7w selected from the plurality of switching elements 6u to 6w and 7u to 7w to be turned on before the normal operation of the motor 5 is started, and the ripple voltage of the dc voltage can be suppressed within the allowable range while the internal temperature of the electrolytic capacitor 1 is increased more quickly.

This can avoid destruction of the electrolytic capacitor 1 in a low-temperature environment, and shorten the time of warm-up operation (non-operation time) required from the start instruction to the start of rotation of the motor 5.

In the embodiment, the control device 3 changes the rate of increase of the current flowing through the motor 5 based on the input voltage HV and the ambient temperature Tc detected by the temperature sensor 4, and thus the internal temperature of the electrolytic capacitor 1 can be increased more safely and efficiently by the warm-up operation.

In this case, in the embodiment, the higher the input voltage HV is, the more the control device 3 changes the rate of increase of the current flowing through the motor 5 in the direction of decrease, so that the internal temperature of the electrolytic capacitor 1 can be safely and quickly increased by the warm-up operation.

In the embodiment, the higher the input voltage HV is, the more the control device 3 changes the value of the current flowing through the motor 5 in the direction of decreasing at the start of the warm-up operation, so that it is possible to more effectively avoid the breakdown of the electrolytic capacitor 1 due to the ripple voltage of the dc voltage.

In the embodiment, the control device 3 changes the rate of increase of the current flowing through the motor 5 in the direction of decrease as the ambient temperature Tc detected by the temperature sensor 4 decreases, so that the internal temperature of the electrolytic capacitor 1 can be increased safely and quickly by the warm-up operation.

In this case, in the embodiment, the lower the ambient temperature Tc detected by the temperature sensor 4, the more the control device 3 changes the value of the current flowing through the motor 5 in the direction of decreasing at the start of the warm-up operation, so that it is possible to more effectively avoid the breakdown of the electrolytic capacitor 1 due to the pulsating voltage of the dc voltage.

In the embodiment, since the control device 3 limits the value of the current flowing through the motor 5 in the normal operation after the completion of the warm-up operation, the electrolytic capacitor 1 can be more effectively prevented from being damaged in the low-temperature environment.

(3) Preheating operation (third)

In an extremely severe environment, that is, in a situation where the ambient temperature Tc is extremely low and the input voltage HV is also extremely high, the control device 3 changes the rate of increase of the current during the warm-up operation stepwise in accordance with the passage of time. This example is shown for the warm-up operating condition in the lower right hand corner of fig. 4. That is, when the ambient temperature Tc of the electrolytic capacitor 1 detected by the temperature sensor 4 is-30 ℃ or lower and the input voltage HV from the battery BAT is 450V or higher and less than 500V, the control device 3 sets the current value at the start of the warm-up operation to 1/10 (one tenth of the normal starting current) and the current value at the time t6 elapses from the start to 2/10 (two tenths of the normal starting current) and starts energization of the motor 5 in the warm-up operation started in step S4 of fig. 2. Then, the current is switched to a state in which the current value at the time of completion of the warm-up operation after the time t6 has elapsed and the time t7 has elapsed is 5/10 (five tenths of the normal starting current).

Thus, as shown in fig. 6, in the motor 5, the current flows at the rate of increase from 1/10 to 2/10 during the energization time t6 from the start of the warm-up operation to the elapsed time t6, and the current flows at the rate of increase from 2/10 to 5/10 during the energization time t7 from the time when the time t6 elapses to the elapsed time t 7. Here, as described above, in the embodiment, the energization time t6 is longer than t7, and the current difference from the start to the elapsed time t6 to the elapsed time t7 after the elapsed time t6 is large, so that the current increase rate from the start to the elapsed time t6 is low, and then the current increase rate to the elapsed time t7 is high. In addition, the change in the stepwise rate of rise can be ensured, and the magnitude relationship between the energization times t6 and t7 is not limited to the embodiment.

Here, since the internal resistance component ESR of the electrolytic capacitor 1 tends to be extremely large at low temperature and to be rapidly reduced with an increase in the internal temperature, the ripple voltage of the dc voltage in the electrolytic capacitor 1 increases from the start of the warm-up operation in fig. 6, but the rate of increase in the current until the time t6 elapses is small, the internal temperature of the electrolytic capacitor 1 increases, and the internal resistance component ESR also rapidly decreases, so MAX1 (maximum value 1) of the ripple voltage is relatively low within the allowable range.

Further, although the rate of increase in the current increases after the time t6 elapses and the time t7 elapses until the completion of the warm-up operation, at this time, the internal resistance component ESR of the electrolytic capacitor 1 significantly decreases, and therefore the ripple voltage does not become equal to or higher than the other MAX2 (maximum value 2) within the allowable range, and then gradually decreases even if the current increases. As described above, in an environment where the ambient temperature Tc and the input voltage HV are extremely severe, the control device 3 changes the rate of increase of the current flowing through the motor 5 in multiple stages (two stages in the embodiment) with the passage of time during the warm-up operation, and changes the rate of increase of the current flowing through the motor 5 in a direction of increasing with the passage of time from the start of the warm-up operation, so that the internal temperature of the electrolytic capacitor 1 can be increased more safely and quickly.

The time axis shown in fig. 6 is not fixed, but is reduced in the portion of the energization time t6 and expanded in the portion of the energization time t7 in order to exaggerate the image. The higher the current axis is, the larger the current axis is.

In the embodiment of fig. 4, the warm-up condition is set based on the input voltage HV and the ambient temperature Tc (the temperature of the electrolytic capacitor 1), but the warm-up condition is not limited to this, and may be set based only on the input voltage HV, or conversely may be set based only on the ambient temperature Tc. However, as in the embodiment, by performing the warm-up operation based on both the input voltage HV and the ambient temperature Tc, it is possible to perform control more accurately.

The warm-up operation in (3) above is performed by changing the rate of increase in current in two stages, but may be performed in more detail in a plurality of stages, i.e., three or more stages.

In the embodiment, the three-phase inverter circuit 2 is described, but the present invention is not limited to this, and the inverter circuit 2 may have several phases such as four phases, for example, or may be set as appropriate according to the number of phases of the motor 5 (electric motor) to be applied.

The inverter device IV is not limited to the vehicle-mounted inverter device of the embodiment, and may be applied to various electrical devices such as a general air conditioner.

Description of the reference symbols

1 electrolytic capacitor

2 inverter circuit

3 control device

4 temperature sensor

5 Motor (Motor)

6 u-6 w, 7 u-7 w switching elements

BAT battery

ESR internal resistance component

IV inverter device.